Process of recovering germanium-containing material from coal



United States Patent PROCESS OF RECOVERING GERMANIUM-CON- TAINING MATERIAL FROM COAL Masaru Inagaki, Sibuya-ku, Tokyo, Japan, assignor to Sekitan Sogo Kenkyujo Zaidan Hojin (Coal Research Institute), Tokyo, Japan, a corporation of Japan Application April 27, 1953, Serial No. 351,191

Claims priority, application Japan January 21, 1952 18 Claims. (Cl. 75-84) This invention relates to the recovery of germanium metal and/or compounds from coal, and more particularly from the aqueous liquor formed during the high temperature carbonization of coals. It has been found that when these coals are carbonized, germanium compounds appear in the aqueous liquor formed as a product of carbonization. This liquor, which contains dissolved organic and inorganic materials, with the former probably predominating, is sometimes termed the gas liquor of coal carbonization. The invention provides for the conversion of these materials, or at least a part of them, to a form which incorporates the germanium and which enables a separation from the gas liquor to be made; and as will be described, it is preferred to precipitate the germanium-containing materials in the liquor and then to remove the precipitate. A convenient and effective procedure for forming the precipitate is to oxidize the gas liquor. Germanium compounds and/or germanium metal may be recovered from the precipitate, preferably by the improved steps described herein.

In brief, the invention involves the discovery that germanium-containing materials are present in the aqueous liquor or gas liquor resulting from the carbonization of coal and comprises the separation of the germanium from the liquor in the form of a precipitate from which pure germanium compounds or germanium metal may be recovered. One of the advantages of the invention is based on the fact that this liquor can be handled and/ or treated through several consecutive steps, it being generally recognized that the ability to process a liquid affords conveniences not found in the processing, say, of solid materials.

Gas liquor from any source may be treated by the present method provided that the germanium content of the liquor is sutliciently high to justify the expense of recovering it; for this purpose the gas liquor should contain at least about 0.001 gram of germanium per liter. Generally, gas liquors may contain from about 0.001 to about 0.01 gram of germanium per liter. The invention further contemplates the actual carbonization of the coal and provides, particularly for certain coals, a preliminary step of treating the coal to isolate a component fraction of it which is richer in germanium than the balance of the coal. This fraction is then carbonized to produce a gas liquor of greater germanium content than otherwise.

The invention may be better understood by referring to the drawings in which are shown flow sheets diagrammatically illustrating various modifications and in which Fig. 1 shows the precipitation of germanium-containing material from gas liquor and the recovery of the germanium; Fig. 2 illustrates a method for carbonizing coal and treating the gas liquor resulting therefrom and also a procedure for processing another product of carbonization; Fig. 3 illustrates the carbonization of coal to produce gas liquor and the subsequent treatment of the latter; and Fig. 4 shows the recovery of'germanium compounds ice and germanium metal from the germanium-containing precipitate formed in the gas liquor.

As illustrated in the flow sheet of Fig. 1, gas liquor from a suitable source is subjected to a treating step in which germanium-containing material is precipitated. This step may comprise an oxidation of the gas liquor with an oxidizing agent in zone 10 or a treatment of the liquor with a metallic salt in zone 11. The oxidation step produces a reactionmixture a part of which is in the form of a precipitate and the balance of which is a colloidal solution. Prior to the oxidation step, the gas liquor comprises a single phase true solution. Ordinary oxidizing agents may be employed to carry out the oxidation, such as air, oxygen, ozone, hydrogen peroxide, potassium permanganate, potassium dichromate, ceric sulfate, sodium and potassium nitrates and chlorates, chlorine, bromine, etc. Oxidizing acids may be employed but are not preferred. Air is the preferred agent; and on the basis of 1 ton of gas liquor, the air is usually passed through the liquor at a rate of 5 to 10, and generally not more than 15, cubic meters per hour. The air may be so introduced as to stir the liquor as well as to oxidize, and if desired, independent stirring means.

may be employed. The temperature may range from about 30 to about 100 CL at ordinary pressures. The reaction is carried out until complete, which requires at least a half hour to 2 hours or more. Usually the reaction may be completed within 2 hours. If the reaction is carried out at higher pressures, the reaction time will be shortened and higher temperatures may be used, for example up to 200 C. It is preferred to carry out the oxidation in the liquid phase. With other oxidizing agents, an amount is employed which is equivalent in oxidizing power to the abovedescribed quantities of air; as an example, aqueous solutions of potassium dichromate may be employed containing, for example, 20 to by weight of dichromate; and from 0.03 to 0,01 part by weight of such dichromate solutions may be used for 1 part by weight of 'gas liquor. Solutions of higher or lower dichromate concentrations are also useful, the amount of solution required for the oxidation usually decreasing with increasing dichromate concentration. Nongaseous agents are preferably used in the form of aqueous solutions. The sufliciency of the agent, and the completeness of the reaction, in general, may be readily tested in the manner hereinafter described.

As may be seen, the oxidation step is convenient to perform and, when air is the oxidizing agent, is economical as well as efficient.

The precipitate produced during the oxidation, which contains at least a portion of germanium originally present in the gas liquor, is believed to comprise an organic material of high molecular weight in which the germanium is bound in some way. The presence of germanium in the material can be verified by spectroscopic analysis.

The oxidized, precipitate-containing reaction mixture may be handled in one of two ways: it may be acidified in zone 12 or it may be autoclaved in zone 13. In the acidification step, the pH of the reaction mixture is adjusted to a value below 7.0, or in the range of about pH 1.0 to about pH 7.0, care being taken at the higher pH values to see that the mixture is actually acid. Preferably the pH is adjusted to a value in the range of 1 0 to 4.0; it may extend to 0, but such low values are not usually necessary. The acidification serves to clarify the solution, that is, to coagulate the colloidal particles, and to increase the quantity of precipitate. Any suitable agent may be used to acidify the reaction mixture, including ordinary inorganic acids like hydrochloric, sulfuric, nitric,

I fluosilicic, phosphoric, chlorosulfonic, etc., particularly the mineral acids; also ordinary organic acids like formic,

,acetic,..propionic, tartaric, .lactic, .cresylic,,1auric, and various alkyl and aryl sulfonic acids, etc.; and salts having an acid action in aqueous'solution, such as sodium acid sulfate,-potassiumpacid sulfate,:sodium dihydrogen phos- .Following acidification, the precipitate may be separated in zone 14 as by decantation, filtration, or, preferably, by centrifugation.

To determine whether the oxidation has been complete, the filtrate may at this pointbe brought to the pH of the initialgas liquor and reoxidized, following which the acidity is adjusted as before.

If no further precipitate is formed, the original oxidation is judged to be complete;

any substantial amount of precipitate formed during re- -oxidation is, of course, collectedand added to the first .amount. It is usually foundthata substantially constant .amount of precipitate is obtainable from average gas liquors and that this amount can be obtained without resorting. to reoxidation.

Theprecipitate is subjected to steps, hereinafter described, in zone 15, for the recovery of germanium compounds and/orgermanium metal.

When the oxidized gas liquor is treated in zone 13 instead of zone 12, the result of the autoclaving is to clarify the colloidal'oxidized liquor and to increase the amount of precipitate. The autoclavingstep is carried out at a temperature in the range of 150 to 250 C., with the higher temperatures preferred. The heating is stopped when the amount of precipitate in the oxidized liquor is constant, at which time it is also found that the liquor is no longer colloidal. 'In practice, the heating time may average about half-anhour. .After the mixture has cooled, it

.may bepassed to zone 14for separation of the precipitate -,is..readily separable.

..In order to form the germanium-containing precipitate in the gas liquor. byitreatment with a metallic salt, as in zone VII, the liquor is mixed with a metallic salt, preferably. a salt of a metal which is naturally present in the original gas liquor in the form of a dissolved compound, at ordinary pressures and at temperatures'just below 100 C., or just below boiling, and extending down to room temperatures. A precipitate quickly formsand is believed to comprise a high molecular weight organic material in which the germanium .is held in a manner not-yet fully understood. The precipitate is also believed to incorporate aquantity of ferric-hydroxide since the gas liquor contains iron. It is thought that the metallic salt influences the formation of the precipitate, at least partly, by virtue of an oxidizing action on the materials of the gas liquor. The metallic salt should be soluble in water, and particularly in the gas liquor. :It is preferably employed in the form of anaqueousysolution rangingin concentration from a dilute solution,.say as low as 1% by weight of the salt, to a saturated solution. As. may be appreciated, the amount of metallic salt solution is variable, but generally speaking, amounts from 0.02 to.about.0.4 ton may be employedper ton of gas liquor. Suitable salts are ferric alums, aluminum alums, copper sulfate, zinc chloride,

. ferric chloride, ferric sulfate,,mercuric chloride, zinc sulfate, .copper chloride, mercuric sulfate, -and the. chlorides andsulfates of aluminum. .Preferredsalts.areiron alum {ferric potassium sulfate) and copper sulfate.

arsazeo Following the metallic salt treatment in zone 11, the reaction mixture is preferably passed to zone 17 to insure that the pH. of the mixture is at a proper value and thus help to develop the precipitate and to increase its quantity. The pH may range from-Oto-about 7.0, preferably from 1.0 to 4.0; at a pH near 7.0, the mixture should be on the acid side. The actual'treating step in zone-17 is like that in zone 12, described'above. It is sometimes possible, as where the pH of the mixture is below pH 7.0, to pass the mixture from zone 11 directly to zone 13 for separation of the precipitate, the separation being'performed as described in connection with zone 14.

As indicated in Fig. 1, the mixture from zone 11 may be autoclaved in zone 19 to aid in completing the precipitat' n the germanium-containing material, the autoclaving ions being iikethose used in "zone 13. After autola.rng, the mixture may be passed to zone 20, if necessary,.fer adjustment of its pH in the manner noted for zone 16, or it .may :besent directly to zone 13. The precipitate from the latter zone is subjected to the germanium recovery steps indicated in zone 15.

in Fig. 1, it will be seen that the treatment of the gas liquor in'zone or 1.1 is by means of an agent which effects an oxidation and a precipitation of at least part of the contents of the gas liquor, with the precipitatc containing at least a part of the germanium present in the gas liquor.

Referring to Fig. 2, in which a method for carrying out the invention is illustrated, a bituminous caking coal is first reated in zone to separate the vitrain component in which, it has been found, the germanium tends to be concentrated. The treatment comprises a petrographical or physical separation, for which several procedures, are available. In one procedure, the coal is crushed, the vitrain or bright component being more friable than the durain or dull component so as to produce a finer powder which may be separated from the durain by screening. Another procedure is based on the electrostatic properties of the vitrain and durain components and comprises feeding the pulverized coal between differently charged electrodes; the vitrain material is attracted to one electrode and the durain to the other. Still another procedure is a flotation method based on the. fact that the vitrain floats more easily than the durain.

The vitrain component, which in Japanese coals may range from 25 to 60% and in U. S. or European coals from to 70%, is then subjected to a high temperature carbonization, as indicated at 26. In this operation the temperature should be above 800 C. and preferably in therange of 1000 to 1200 C. The carbonization reaction per se is conventional, but as noted above, it is the discovery of germanium compounds in the gas liquor or aqueous fraction resulting from the carbonization that concerns the invention, and particularly the recovery of such compounds. The volatile products of carbonization, which comprise, broadly speaking, a mixture of gases, vapors, and finely divided liquid particles, are washed and cooled in zone 27'with previously formed gas liquor which is recirculated through lines 28 and 29, a portion also being sent through line 30 to cool the volatile products as they emerge from the carbonizing oven. Water orweakly alkaline aqueous solutions comprising 0.01 to 5%, usually 0.1 to 3%, by weight of alkali. and including solutions of ammonium hydroxide, caustic soda, or sodium bicarbonate, may be employed to wash and cool the volatile carbonization. products, but gas liquor is preferred. The gas liquor comprises a watery solution that is condensed from the volatile prodnets and that contains in solution ammonia, ammonium salts, and anumber of inorganic and organic materials. The water has itsorigin in the coal and/0r may be formed during carbonization.

For the purpose of the inventiomthe separation of the volatile carbonization products into gas liquor and crude tar will be considered, although'it is understood that other products such as gas and hydrocarbon materials are separable therefrom. Gas, for example, may be removed in part at least through line 31. The separation zone is indicated at 32, from which crude tar and gas liquor are removed as indicated. A portion of the gas liquor is recycled, as described, and the remainder is subjected to a product recovery operation in unit 33, which operation, for example, may comprise a steam distillation to remove ammonia and ammonium compounds. This operation may be performed subsequently to the removal of the germanium-containing precipitate from the liquor, but preferably it is done as shown in Fig. 2. The gas liquor remaining from the recovery operation is then subjected to oxidation in zone 34 followed by the pH adjustment step in zone 35, these steps being identical to those employed in zones and 12, respectively, of Fig. 1. The precipitate from zone 35 is next subjected to a series of recovery steps to isolate germanium metal, these steps being collectively indicated at 36 and described below in detail.

To increase the yield of germanium-containing precipitate, it is possible to process the crude tar separated in zone 32. As shown in Fig. 2, the crude tar is extracted in zone 37 with aqueous ammonia liquor, constant stirring being employed during the extraction. A suitable ammonia liquor comprises a solution of about 0.01 to about 5% by weight of ammonia in water, and about 0.1 to about 1.0 part by weight of this liquor is employed to extract 1 part by weight of crude tar. The extraction proceeds at ordinary temperatures, and when it is finished, the phases are separated. The aqueous ammonia phase or fraction, which contains the germanium material, may, if desired, be stripped of its ammonia content before further processing, or it may be passed directly to the oxidation and pH adjusting steps in zones 38 and 39, which steps are like those in zones 34 and 35. It may be noted that the aqueous ammonia fraction is handled separately from the material in zones 34 and 35. The precipitate from zone 39 passes to a recovery zone 40; it may, if desired, be combined with the precipitate from zone 35.

In Fig. 3 the coal may or may not be concentrated prior to carbonization. If the coal is one in which the germanium is concentrated in a component fraction thereof, it is preferred to isolate such fraction in zone by a suitable petrographical separation process of the kind described and then to pass the fraction so isolated to the carbonization zone 46. If the coal is one which does not require or permit a preliminary concentration to be made, such as certain brown coals which comprise mostly ligneous matter, the coal is passed directly to the carbonization zone. From the volatile carbonization products the gas liquor is separated and subjected to oxidation in unit 47. The carbonization and oxidation steps have already been described. The precipitate resulting from step 47 is then separated in zone 4-8 and subjected to a germanium recovery procedure in zone 49.

Fig. 4 illustrates procedures for recovering germanium compounds and germanium metal from the precipitate such as that indicated at 35a and 39a of Fig. 2 and 48a of Fig. 3, and described as collected in zones 14 and 18 of Fig. l. Briefly, the general procedure is to burn the dried precipitate to produce a germanium dioxidecontaining material, then to convert the, dioxide to germanium tetrachloride, then to convert the latter to the dioxide again, and finally to reduce the dioxide to the metal. According to one procedure, the precipitate is burned with a free oxygen-containing gas such as air or oxygen at a temperature below about 450 C. in zone to produce an ash which is collected in zone 56. The germanium content of the ash averages from 1 to 2% by weight. The dioxide is chlorinated by mixing the ash with concentrated hydrochloric acid in zone 57 and distilling the mixture to produce germanium tetrachloride, a liquid boiling at abouty85 C. The tetrachloride. is

then hydrolyzed with water in zone 58, producing a precipitate of germanium dioxide, and the latter is reduced with hydrogen in zone 59 to yield the metal. It may be noted that the germanium tetrachloride may be further purified, if necessary, by refractionation.

An improved and preferred procedure for treating the precipitate comprises burning it with air or oxygen at a temperature above 1000 C. in zone 60 to form a volatile germanium dioxide-containing dust which is collected in zone 61. The germanium content of the dust may run from 10 to 40% by weight. It has been found that heavy oxides like ferric oxide and aluminum oxide, which are formed in zones 55 and 60, do not tend to concentrate in the dust collected in zone 61; thus a separation from these latter oxides is possible and a material of higher germanium dioxide content may be obtained than is produced in zone 5s and collected in zone 56. It is possible to pass the material in zone 61 directly to the reducing zone 59 for conversion to the metal, but for a purer metal it is preferred to treat the dust in zone 61 according to the steps described in zones 57, 58, and 59.

Whenever the germanium dioxide produced by the hydrolysis reaction in zone 58 is not sufiiciently pure, it is possible to convert it to the tetrachloride, as in zone 57, then isolate the tetrachloride, and then convert the latter to a purer dioxide. A purer dioxide produces a purer metal.

The coals with which the invention is concerned are, of course, those containing germanium. The presence of germanium in the coal is determinable beforehand as by means of a spectroscopic analysis. The germanium content of the coal material charged to the carbonizing oven may vary from 0.0001 to 0.001%, and at the most from 0.0003 to 0.2% germanium, by weight. Coals that are particularly suitable for being carbonized to form gas liquor are caking coals, which includes most bituminous coals. As noted, an advantage of a bituminous coal is the ability to isolate from it a fraction of greater germanium content than the rest of the coal. Another suitable coal for carbonizing is brown coal or lignite containing ligneous matter; some varieties, like Kumanokura coal from Japan, contain a ligneous fraction of greater germanium content than the rest of the coal, and some varieties, like Iutan coal from Japan, are composed substantially entirely of ligneous matter containing germanium. Blends of coal may be used, one particular example being a 50-50 mixture of bituminous coals from the United States and Japan; other blends may comprise bituminous caking coal with one or more other coals like anthracite, bituminous, brown coal, and peat. Gas liquors that are suitable for processing comprise those produced by the carbonization of the foregoing coals and coal blends. As noted above, the gas liquor should contain at least about 0.001 gram of germanium per liter. In some cases, liquors may be processed which result from the subsequent washing of the gas leaving zone 27 through line 31, note Fig. 2.

It may be noted that the method of the invention does not interfere with the normal utilization of the coal or of the coal carbonization products.

The following examples may help to illustrate the invention:

Example 1 One hundred tons of a Kayanuma coal from Japan, a strongly caking bituminous coal, were subjected in subdivided form to electrostatic separation to produce 40 tons of vitrain component. The latter was subjected to carbonization at a temperature in the range of 1000 to 1100 C. over a period of about 12 hours. An aqueous or gas liquor fraction was accumulated from the carbonization products, and this fraction, totaling about 4 tons and havng a pH of about 8.6, was charged to a reactor vessel to be oxidized. The liquor was oxidized at a temperature of. about 65 C. and atmospheric pressure mam bypassing about 10 cubic meters of air per hour through the liquor for 2 to 3 hours. During the course of the oxidation, a precipitate formed on the bottom of the vessel and the solution became colloidal. Following the oxidation, the acidity of the oxidized reaction mixture was adjusted to a pH in the range of 2.0 to 3.0 by adding about 8 kg. of concentrated sulfuric acid to the mixture in the reaction vessel. The precipitate was allowed to settle and when the supernatant liquid became clear it was removed by decantation. The remaining wet precipitate was filtered and dried, a total or about 4 kg. of moisture-free material being obtained. The dried precipitate was burned with air at a temperature in the range of 1000 to 1150 C. in a small furnace having means for collecting the volatile dust produced during the burning step. The burning was continued until no more dust was produced, and then the collected dust, totaling about 0.04 kg, was mixed with about 120 ml. of a 31% hydrochloric acid solution and distilled. Germanium tetrachloride, boiling point 85 C., was obtained as distillate. The tetrachloride was hydrolyzed with water to produce a precipitate of germanium dioxide which,v after filtration, washing and drying, totaled about 6 grams. The germanium dioxide was conventionally reduced with hydrogen to give the metal. About 4.0 grams of germanium were obtained, the purity of which was greater than 99.99%.

Example 2 One hundred tons of Yubari coal from Japan, a bituminous caking coal, was processed by electrostatic separation to give 60 tons of vitrain, and this was carbonized at a temperature of 10001100 C. over a period of 20 hours. The gas liquor fraction obtained from the carbonization products amounted to about 6 tons and had a pH of about 9.2. This liquor was oxidized with air for 45 minutes at a temperature of 150 C. and a pressure of 5 to 6 atmospheres, using about 3 tons of air. The reaction mixture was in the liquid phase during the oxidation. The mixture was acidified to a pH of 2.03.0 by adding 6 kg. of concentrated sulfuric acid, and after the precipitate had settled, the clear supernatant liquid was removed by decantation. The moisture-free precipitate totaled about kg. It was burned with air at a temperature below 450 C. to produce about 1 kg. of ash which was taken up in about 2000 ml. of 31% hydrochloric-acid solution, and the liquid mixture was distilled. A germanium tetrachloride distillate fraction was recovered as in Example 1, hydrolyzed with water to yield 8 grams of germanium dioxide, and this was reduced to germanium metal. The yield of metal was 5.2 grams of a purity above 99.99%.

Example 3 A charge of 100 tons of lutan brown coal from Japan, comprising mostly ligneous matter, was carbonized at 1000 to 1050 C. for 10 hours. The yield of gas liquor, having a pH of about 8.0, was tons. The gas liquor was oxidized at 5060 C. and atmospheric pressure by passing about 10 cubic meters of air per hour through the liquor for a period of two to three hours. The oxidized reaction mixture was acidified to a pH of 2.0-3.0 with 15 kg. of concentrated sulfuric acid, and the precipitate was recovered as described in Example 1. About 30 kg. of moisture-free precipitate were obtained. It was burned with air at a temperature under 450 C., producing about 3 kg. of ash. The ash was treated as in Example 2, the yield of germanium dioxide being 24 gms, and the yield of germanium metal was 16.1 gins. with a purity in excess of 99.99%.

Example 4 To 1 liter of gas liquor obtained from Takashima bituminous coal from Japan by carbonization, there were added 60 cc. of an aqueous solution of iron alum, 1' cc.

. 8 of the latter being equivalent to 10 mg. of iron. The mixture was stirred well at room temperature and then allowed to stand for several hours. It had a pH of 6.5. It was filtered and the precipitate collected. To the filtrate 30 cc. of the same iron alum solution were added, and the mixture stirred and allowed to stand as before. It was then filtered and the precipitate combined with the first precipitate, a total of about 0.9 gram of precipitate being obtained. The germanium content of the precipitate was determined spectroscopically to be in the range of 0.07 to 0.1% by weight; it is recoverable by the procedures described in connection with Fig. 4. By the procedure illustrated in this example, it is possible to remove more than of the germanium content of the gas liquor.

This application is a continuation-in-part of copending application, Serial No. 339,443, filed February 27, 1953, which in turn is a continuation-in-part of copending application, Serial No. 332,103, filed January 19, 1953 and both applications now abandoned.

In the light of the foregoing description, the following is claimed:

1. Method for recovering a germanium-containing material from a bituminous caking coal containing germaniurn which comprises physically separating a vitrain fraction from said coal by means of a conventional separating procedure, subjecting said vitrain fraction to carbonization at a temperature in the range of 800 to 1200 C. to produce volatile carbonization products, initially cooling said volatile products with an aqueous liquor previously condensed and recovered from previously formed products of like nature, then washing and further cooling said volatile products with another portion of said aqueous liquor to separate said products into a gas fraction and a heavier traction, separating the heavier fraction into a tar fraction and an aqueous liquor fraction, recirculating portions of the latter to cool and wash subsequently produced volatile carbonization subjecting another portion of the aqueous liquor fraction to oxidation at a temperature of about 30 to about C. at atmospheric pressure and in the presence of an oxidizing agent, adjusting the pH of the oxidized aqueous liquor to a pH in the range of 1.04.0, forming a germanium-containing precipitate in said aqueous liquor as a result of said oxidation and pH adjustment steps, separating said precipitate from the aqueous liquor, burning the precipitate to produce a material more concentrated with respect to germanium than said precipitate, and recovering said material.

2. Method for recovering a germanium-containing material from a bituminous caking coal containing germanium which comprises physically separating a vitrain fraction from said coal by means of a conventional separating procedure, subjecting said vitrain fraction to carbonization at a temperature in the range of 800 to 1200 C. to produce volatile carbonization products, condensing and separating from said volatile products an aqueous liquor and subjecting said liquor to oxidation at a temperature of about 30 to about 100 C. at atmospheric pressure and in the presence of an oxidizing agent, adjusting the pH of the oxidized aqueous liquor to a pH in the range of 1.0-7.0, forming a germanium-containing precipitate in said aqueous liquor as a result of said oxidation and pH adjustment steps, separating said precipitate from the aqueous liquor, burning the precipitate to produce a material more concentrated with respect to germanium than said precipitate, and recovering said material.

3. Method of claim 2 wherein said material contains germanium dioxide, which comprises the steps of mixing said material with concentrated hydrochloric acid solution to convert the germanium dioxide to germanium tetrachloride, distilling the germanium. tetrachloride from the conversion mixture, hydrolyzing the tetrachloride as e s? with water to germaniumdioxide, and then reducing the dioxide to germanium metal.

r ,4. Method for recovering a germanium-containing material from a caking coal by means of a conventional separating procedure containing germanium which comprises physically separating from said coal'a fraction having a higher content of germanium thanjother fractions thereof, subjecting said fraction to carbonization at a temperature in the range of 800 to 1200" C. to produce an aqueous liquor product, oxidizing said aqueous liquor product to form a germanium-containing precipitate in said aqueous liquor, separating said precipitate from the aqueous liquor, burning the precipitate to produce a material more concentrated with respect to germanium than said precipitate, and recovering said material.

5. Method for recovering a-germaniumcontaining material from gas liquor containing the same, said gas liquor being derived from the carbonization of a germanium containing coal at 800 to 1200 C., which comprises subjecting the liquor to oxidation in the presence of an oxidizing agent, autoclaving the oxidized liquor, forming a germanium-containing precipitate in said liquor as a result of said oxidation and autoclaving steps, separating said precipitate from the liquor, burning the precipitate to produce a material more concentrated with respect to germanium than said precipitate, and recovering said material.

6. Method for recovering a germanium-containing material from a eaking coal containing germanium which comprises subjecting the coal to carbonization at a temperature in the range of 800 to 1200 C. to produce volatile carbonization products, washing and cooling said volatile products with an aqueous liquor previously condensed and recovered from previously formed products of like nature, recovering the resulting aqueous liquor and a tar fraction, recirculating a portion of said resulting aqueous liquor to wash and cool subsequently produced volatile products, subjecting another portion of said resulting aqueous liquor to oxidation at a temperature of about 30 to about 100 C. at atmospheric pressure and in the presence of an oxidizing agent, adjusting the pH of the oxidized liquor to an acid pH in the range of about 1.0 to about 7.0, forming a precipitate in said oxidized liquor as a result of the oxidation and pH adjusting steps, separating said precipitate from the liquor, then burning the precipitate with a free oxygen-containing gas at a temperature above 1000 C. to produce a volatile dust containing germanium dioxide, collecting said dust as said germanium containing material; extracting said tar fraction with about 0.1 to about 1.0 part by weight of an ammoniacal liquor comprising about 0.01 to about by weight of ammonia and the balance substantially water, separating from said extraction step the aqueous extract fraction and subjecting the same to oxidation at about 30 to about 100 C. at atmospheric pressure in the presence of an oxidizing agent, adjusting the pH of the oxidized aqueous fraction to an acid pH of about 1.0 to about 7.0, forming a precipitate in said aqueous fraction as a result of said oxidation and pH adjustment steps, separating the precipitate from said aqueous fraction, and recovering a germanium-containing material from said precipitate in the manner described above in connection with the treatment of the precipitate obtained from said resulting aqueous liquor.

7. Method for recovering a germanium-containing material from gas liquor containing the same, said gas liquor being derived from the carbonization of a germanium-containing coal at 800 to 1200 C., which comprises oxidizing said gas liquor to form a germanium-containing precipitate in said liquor, separating said precipitate from the liquor, burning the precipitate with a free oxygen-containing gas at a temperature above 1000 C. to produce a volatile dust containing germanium dioxide, the concentration of germanium in said dust being higher than in said precipitate, collecting said dust and recovering said dust as said germanium-containing compound.

8. Method for recovering a germanium-containing material from gas liquor containing the same, said gas liquor being derived from the carbonization of a germaniumcontaining coal at 800 to 1200 C., which comprises oxidizing said gas liquor to form a germanium containing preclpitate in said liquor, separating said precipitate from the liquor, burning the precipitate with a free oxygencontaining gas at a temperature below about 450 C. to produce an ash containing germanium dioxide, and collecting said ash as said germanium-containing material.

9. Method for recovering a germanium-containing material from a coal containing the same which comprises subjecting the coal to carbonization at a temperature in the range of 800 to 1200 C. to produce volatile carbonization products, condensing and recovering from said products an aqueous liquor containing germanium, subjecting the aqueous liquor to treatment with an inorganic metal salt by mixing the salt with the liquor, said salt being soluble in Water and in said liquor and being a salt of a metal originally present in said liquor in dissolved form, said salt being further characterized by forming a germanium-containing precipitate in said liquor, separating said precipitate from the liquor, burning the precipitate to produce a material more concentrated with respect to germanium than said precipitate, and recovering said material.

10. Method of claim 9 in which said metallic salt is a salt of a metal selected from the group consisting of iron, aluminum, copper, zinc, and mercury.

11.. Method of claim 10 in which said metallic salt is selected from the class consisting of sulfates and chlorides.

12. Method of claim 10 in which said metallic salt is an iron alum.

13. Method for recovering a germanium-containing material from gas liquor containing the same, said gas liquor being derived from the carbonization of a ger manium-containing coal at 800 to 1200 C., which comprises subjecting the liquor to oxidation in the presence of an oxidizing agent, insuring that the pH of the oxidized liquor has an acid pH in the range of 1.0 to 7.0, forming a germanium-containing precipitate in said liquor as a result of said oxidation step and said pH insuring step, separating said precipitate from the oxidized liquor, burn ing the precipitate to produce a material more concentrated with respect to germanium than said precipitate, and recovering said material.

14. Method for recovering a germanium-containing material from gas liquor containing the same, said gas liquor being derived from the carbonization of a germanium-containing coal at 800 to 1200 C., Which comprises adding an inorganic metallic salt to said liquor and mixing the same, said salt being soluble in Water and in said liquor and being a salt of a metal originally present in the gas liquor in dissolved form, then insuring that the pH of the liquor has an acid pH in the range of 1.0-7 .0, forming a germanium-containing precipitate in said liquor as a result of said salt addition step and said pH insuring step, separating said precipitate from the liquor, burning the precipitate to produce a material more concen trated with respect to germanium than said precipitate, and recovering said material.

15. Method for recovering a germanium-containing material from a coal containing the same which comprises subjecting the coal to carbonization at a temperature in the range of 800 to 1200 C. to produce volatile carbonization products, condensing and recovering from said products an aqueous liquor containing germanium, oxidizing said aqueous liquor to form a germanium-containing precipitate in said aqueous liquor, separating said precipitate from the aqueous liquor, and recovering said precipitate as said germanium-containing material.

16. Method for recovering a germanium-containing material from a caking coal containing germanium which comprises subjecting the coal to carbonization at a temperature in the range of 800 to 1200" C. to produce volatile carbonization products, washing and cooling said volatile products with an aqueous liquor previously condensed and recovered from previously formed products of like nature, recovering the resulting aqueous liquor and a crude tar fraction, recirculating a portion of said resulting aqueous liquor to wash and cool subsequently produced volatile products, subjecting another portion of said resulting aqueous liquor to oxidation, adjusting the acidity of the oxidized aqueous liquor to an acid ph below pH 7.0, forming a germanium-containing precipitate in said aqueous liquor as a result or" said oxidation and pH adjustment steps, separating said precipitate from the aqueous liquor, burning the precipitate to produce a material more concentrated with respect to germanium than said precipitate, and recovering said material; extracting said crude tar fraction with an aqueous ammonia liquor, separating the aqueous ammonia fraction from the extraction step and oxidizing the same, adjusting the pH of the oxidized aqueous ammonia fraction to an acid pH below pH 7.0, forming a germanium-containing precipitate in said fraction as a result of said oxidizing and pH adjusting steps, separating said precipitate, burn ing the precipitate to produce a material more concentrated with respect to germanium than said precipitate, and recovering said material.

References Cited in the file of this patent UNITED STATES PATENTS 1,848,246 Mitchell .s. Mar. 8, 1932 2,588,008 Jones Mar. 4, 1952 FOREIGN PATENTS 715,581 France Sept. 28, 1931 OTHER REFERENCES Chemistry and Industry, vol. 56, pages 717721, Aug. 7, 1937. (Copy in Scientific Library.)

Journal of Applied Chemistry, vol. 1, pages 541-551. December 1951. (Copy in Scientific Library.)

Journal of Metals, pages 1132-1137, Nov, 1952. 

5. METHOD FOR RECOVERING A GERMANIUM-CONTAINING MATERIAL FROM GAS LIQUOR CONTAINING THE SAME, SAID GAS LIQUOR BEING DERIVED FROM THE CARBONIZATION OF A GERMANIUMCONTAINING COAL AT 800 TO 1200*C. WHICH COMPRISES SUBJECTING THE LIQUOR TO OXIDATION IN THE PRESENCE OF AN OXIDIZING AGENT, AUTOCLAVING THE OXIDIZED LIQUOR, FORMING A GERMANIUM-CONTAINING PRECIPITATE IN SAID LIQUOR AS A RESULT OF SAID OXIDATION AND ZUTOCLAVING STEPS, SEPARATING SAID PRECIPITATE FROM THE LIQUOR, BURNING THE PRECIPITATE TO PRODUCE A MATERIAL MORE CONCENTRATED WITH RESPECT TO GERMANIUM THAN SAID PRECIPITATE AND RECOVERING SAID MATERIAL. 